<!DOCTYPE html>
<html lang="en">
<body style="background-color: aqua">
    <!--
    背景
    1. 固定的颜色
    2. 图片
    3. 透明度
    -->
<div style="width: 600px;height: 600px;background-color: red;
background-image: url('http://hmkcloud.cn/usr/themes/handsome/assets/img/sj/2.jpg');background-size: 60px 60px;
background-repeat: repeat-x;
opacity: 100%">
    <!--  background-repeat
            no-repeat   不重复
             repeat-x   X轴重复
      opacity 不透明度 100% | 0-1
    -->
</div></body>
</html>